Tabesh Jalal, Mahdavi Maziyar, Haddadi Gholamhasan, Ravanfar Haghighi Rezvan, Jalli Reza
MSc, Department of Radiology, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran.
PhD, Department of Radiology, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran.
J Biomed Phys Eng. 2021 Aug 1;11(4):447-458. doi: 10.31661/jbpe.v0i0.2105-1322. eCollection 2021 Aug.
The diagnostic reference level (DRL) is measured with different methods in the common Computed tomography (CT) exams, but it has not been measured through the size-specific dose estimate (SSDE) method in Iran, yet.
This study aimed to calculate the local DRL (LDRL) using the new quality control-based dose survey method (QC) and patients' effective diameter (MQC) and compare them with a data collection method (DC) as well as local national DRLs (NDRL).
In this cross-sectional study, LDRL, based on the third quartile of volumetric computed tomography dose index (CTDI) and dose length product (DLP) values, was calculated for the four common CT examinations in four CT scan centers affiliated with Shiraz University of Medical Sciences by DC, QC and MQC methods. The CTDI of each patient for each CT exam calculated with three methods was compared with paired t-test. Also, the LDRL using MQC method was compared with other national DRL studies.
There was a significant difference between the CTDI values calculated with MQC and QC in all four examinations (P <0.001). The LDRL based on CTDI obtained by the MQC method for head, sinus, chest, abdomen, and pelvis were (50, 18, 15, 19) mGy, respectively, and the calculated DLP values were also (735, 232, 519, 984) mGy.cm.
In MQC, LDRL based on CTDI was calculated with a mean difference percentage of (19.2 ± 11.6)% and (27.1 ± 8.1)% as compared to the QC and DC methods, respectively. This difference resulted from the use of the SSDE method and dose accuracy in the QC dose survey.
在常见的计算机断层扫描（CT）检查中，诊断参考水平（DRL）采用不同方法进行测量，但伊朗尚未通过特定尺寸剂量估计（SSDE）方法进行测量。
本研究旨在使用基于质量控制的新剂量调查方法（QC）和患者有效直径（MQC）计算局部DRL（LDRL），并将其与数据收集方法（DC）以及当地国家DRL（NDRL）进行比较。
在这项横断面研究中，通过DC、QC和MQC方法，为设拉子医科大学附属的四个CT扫描中心的四项常见CT检查计算基于容积CT剂量指数（CTDI）和剂量长度乘积（DLP）值第三四分位数的LDRL。用配对t检验比较三种方法计算的每次CT检查中每位患者的CTDI。此外，将使用MQC方法的LDRL与其他国家DRL研究进行比较。
在所有四项检查中，MQC和QC计算的CTDI值之间存在显著差异（P<0.001）。通过MQC方法获得的基于CTDI的头部、鼻窦、胸部、腹部和骨盆的LDRL分别为（50、18、15、19）mGy，计算的DLP值也分别为（735、232、519、984）mGy·cm。
在MQC中，基于CTDI的LDRL与QC和DC方法相比，计算的平均差异百分比分别为（19.2±11.6）%和（27.1±8.1）%。这种差异源于QC剂量调查中SSDE方法的使用和剂量准确性。
